Question

是否可以对ImageView的内容执行投影？

不是正方形，而是在ImageView的非透明内容上执行的对象投影。

Like this

Answer 1

这取自Romain Guy在Devoxx的演讲，pdf发现here

由于您已将图像转换为位图，请尝试如下

Paint mShadow = new Paint(); 
// radius=10, y-offset=2, color=black 
mShadow.setShadowLayer(10.0f, 0.0f, 2.0f, 0xFF000000); 
// in onDraw(Canvas) 
canvas.drawBitmap(bitmap, 0.0f, 0.0f, mShadow);

希望这有帮助。

有关详细信息，请参阅此answer

注意

不要忘记Honeycomb及以上你需要调用 setLayerType（LAYER_TYPE_SOFTWARE，mShadow），否则你不会看到你的影子！
SetShadowLayer不适用于硬件加速不幸的是，它大大降低了表现[1] [2]

Answer 2

我遇到了同样的问题，不得不快速解决问题。这可能不是最佳解决方案，但我的修复是添加

         android:adjustViewBounds="true"

在图像视图上，然后将SAME图像设置为源作为背景。这样，背景与源图像的大小和形状相同，因此阴影看起来很自然，因为android中的阴影基于ui元素背景。

Answer 3

使用此类在位图上绘制阴影

public class ShadowGenerator {

    // Percent of actual icon size
    private static final float HALF_DISTANCE = 0.5f;
    public static final float BLUR_FACTOR = 0.5f/48;

    // Percent of actual icon size
    private static final float KEY_SHADOW_DISTANCE = 1f/48;
    public static final int KEY_SHADOW_ALPHA = 61;

    public static final int AMBIENT_SHADOW_ALPHA = 30;

    private static final Object LOCK = new Object();
    // Singleton object guarded by {@link #LOCK}
    private static ShadowGenerator sShadowGenerator;

    private  int mIconSize;

    private final Canvas mCanvas;
    private final Paint mBlurPaint;
    private final Paint mDrawPaint;
    private final Context mContext;

    private ShadowGenerator(Context context) {
        mContext = context;
        mCanvas = new Canvas();
        mBlurPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
        mBlurPaint.setMaskFilter(new BlurMaskFilter(mIconSize * BLUR_FACTOR, Blur.NORMAL));
        mDrawPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
    }

    public synchronized Bitmap recreateIcon(Bitmap icon) {
        mIconSize = Utils.convertDpToPixel(mContext,3)+icon.getWidth();
        int[] offset = new int[2];
        Bitmap shadow = icon.extractAlpha(mBlurPaint, offset);
        Bitmap result = Bitmap.createBitmap(mIconSize, mIconSize, Config.ARGB_8888);
        mCanvas.setBitmap(result);

        // Draw ambient shadow
        mDrawPaint.setAlpha(AMBIENT_SHADOW_ALPHA);
        mCanvas.drawBitmap(shadow, offset[0], offset[1], mDrawPaint);

        // Draw key shadow
        mDrawPaint.setAlpha(KEY_SHADOW_ALPHA);
        mCanvas.drawBitmap(shadow, offset[0], offset[1] + KEY_SHADOW_DISTANCE * mIconSize, mDrawPaint);

        // Draw the icon
        mDrawPaint.setAlpha(255);
        mCanvas.drawBitmap(icon, 0, 0, mDrawPaint);

        mCanvas.setBitmap(null);
        return result;
    }



    public static ShadowGenerator getInstance(Context context) {

        synchronized (LOCK) {
            if (sShadowGenerator == null) {
                sShadowGenerator = new ShadowGenerator(context);
            }
        }
        return sShadowGenerator;
    }

}

向ImageView添加投影

3 个答案: